jQuery.extend({

  createUploadIframe: function(id, uri) {
    // create frame
    var frameId = 'jUploadFrame' + id;
    var iframeHtml = '<iframe id="' + frameId + '" name="' + frameId + '" style="position:absolute; top:-9999px; left:-9999px"';
    if (window.ActiveXObject) {
      if (typeof uri == 'boolean') {
        iframeHtml += ' src="' + 'javascript:false' + '"';

      } else if (typeof uri == 'string') {
        iframeHtml += ' src="' + uri + '"';

      }
    }
    iframeHtml += ' />';
    jQuery(iframeHtml).appendTo(document.body);

    return jQuery('#' + frameId).get(0);
  },
  createUploadForm: function(id, fileElementId, data) {
    // create form
    var formId = 'jUploadForm' + id;
    var fileId = 'jUploadFile' + id;
    var form = jQuery('<form  action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data"></form>');
    if (data) {
      for ( var i in data) {
        jQuery('<input type="hidden" name="' + i + '" value="' + data[i] + '" />').appendTo(form);
      }
    }
    var oldElement = jQuery('#' + fileElementId);
    var newElement = jQuery(oldElement).clone();
    jQuery(oldElement).attr('id', fileId);
    jQuery(oldElement).before(newElement);
    jQuery(oldElement).appendTo(form);

    // set attributes
    jQuery(form).css('position', 'absolute');
    jQuery(form).css('top', '-1200px');
    jQuery(form).css('left', '-1200px');
    jQuery(form).appendTo('body');
    return form;
  },

  ajaxFileUpload: function(s) {
    // TODO introduce global settings, allowing the client to modify them for
    // all requests, not only timeout
    s = jQuery.extend({}, jQuery.ajaxSettings, s);
    var id = new Date().getTime()
    var form = jQuery.createUploadForm(id, s.fileElementId, (typeof (s.data) == 'undefined' ? false : s.data));
    var io = jQuery.createUploadIframe(id, s.secureuri);
    var frameId = 'jUploadFrame' + id;
    var formId = 'jUploadForm' + id;
    // Watch for a new set of requests
    if (s.global && !jQuery.active++) {
      jQuery.event.trigger("ajaxStart");
    }
    var requestDone = false;
    // Create the request object
    var xml = {}
    if (s.global) jQuery.event.trigger("ajaxSend", [xml, s]);
    // Wait for a response to come back
    var uploadCallback = function(isTimeout) {
      var io = document.getElementById(frameId);
      try {
        if (io.contentWindow) {
          xml.responseText = io.contentWindow.document.body ? io.contentWindow.document.body.innerHTML : null;
          xml.responseXML = io.contentWindow.document.XMLDocument ? io.contentWindow.document.XMLDocument : io.contentWindow.document;

        } else if (io.contentDocument) {
          xml.responseText = io.contentDocument.document.body ? io.contentDocument.document.body.innerHTML : null;
          xml.responseXML = io.contentDocument.document.XMLDocument ? io.contentDocument.document.XMLDocument : io.contentDocument.document;
        }
      } catch (e) {
        jQuery.handleError(s, xml, null, e);
      }
      if (xml || isTimeout == "timeout") {
        requestDone = true;
        var status;
        try {
          status = isTimeout != "timeout" ? "success" : "error";
          // Make sure that the request was successful or notmodified
          if (status != "error") {
            // process the data (runs the xml through httpData regardless of
            // callback)
            var data = jQuery.uploadHttpData(xml, s.dataType);
            // If a local callback was specified, fire it and pass it the data
            if (s.success) s.success(data, status);

            // Fire the global callback
            if (s.global) jQuery.event.trigger("ajaxSuccess", [xml, s]);
          } else
            jQuery.handleError(s, xml, status);
        } catch (e) {
          status = "error";
          // sshandleError(s, xml, status, e);
          jQuery.handleError(s, xml, status, e);
        }

        // The request was completed
        if (s.global) jQuery.event.trigger("ajaxComplete", [xml, s]);

        // Handle the global AJAX counter
        if (s.global && !--jQuery.active) jQuery.event.trigger("ajaxStop");

        // Process result
        if (s.complete) s.complete(xml, status);

        jQuery(io).unbind()

        setTimeout(function() {
          try {
            jQuery(io).remove();
            jQuery(form).remove();

          } catch (e) {
            jQuery.handleError(s, xml, null, e);
          }

        }, 100)

        xml = null

      }
    }
    // Timeout checker
    if (s.timeout > 0) {
      setTimeout(function() {
        // Check to see if the request is still happening
        if (!requestDone) uploadCallback("timeout");
      }, s.timeout);
    }
    try {

      var form = jQuery('#' + formId);
      jQuery(form).attr('action', s.url);
      jQuery(form).attr('method', 'POST');
      jQuery(form).attr('target', frameId);
      if (form.encoding) {
        jQuery(form).attr('encoding', 'multipart/form-data');
      } else {
        jQuery(form).attr('enctype', 'multipart/form-data');
      }
      jQuery(form).submit();

    } catch (e) {
      jQuery.handleError(s, xml, null, e);
    }

    jQuery('#' + frameId).load(uploadCallback);
    return {
      abort: function() {
      }
    };

  },

  uploadHttpData: function(r, type) {
    var data = !type;
    data = type == "xml" || data ? r.responseXML : r.responseText;
    // If the type is "script", eval it in global context
    if (type == "script") jQuery.globalEval(data);
    // Get the JavaScript object, if Text is used
    if (type == "text") data = jQuery(data).text();
    // If the type is "script", eval it in global context
    if (type == "json") data = jQuery.parseJSON(jQuery(data).text());
    // evaluate scripts within html
    if (type == "html") jQuery("<div>").html(data).evalScripts();

    return data;
  },

  handleError: function(s, xhr, status, e) {
    // If a local callback was specified, fire it
    if (s.error) {
      s.error.call(s.context || window, xhr, status, e);
    }

    // Fire the global callback
    if (s.global) {
      (s.context ? jQuery(s.context) : jQuery.event).trigger("ajaxError", [xhr, s, e]);
    }
  }
})
